The present invention generally relates to portable electronic devices with a communication function, such as electronic notebooks and electronic memo pads, that can display upper-case letters but not lower-case letters, and more particularly to a letter data processing for such a portable electronic device for the display of data received and the reverse transmission of received data.
With a line-up of compatible products, it is often possible to connect up portable electronic devices with a communication function (such as electronic notebooks and electronic memo pads) with superior kinds of portable electronic devices and information processing devices (such as personal computers and word processors) so as to effect two-way data transmission.
Of the inferior kinds of portable electronic devices, there are some that can display upper-case letters but not lower-case letters.
Thus when data transmission is effected between a portable electronic device or information processing device of a superior kind that can display both upper-case letters and lower-case letters (referred to as a first device below) and an inferior kind of portable electronic device that can only display the alphabet in upper-case letters (referred to as a second device below), lower-case letter codes contained in data received by the second device from the first device are converted into upper-case letter codes, the data being stored after conversion.
FIGS. 5(A), 5(B) and 5(C) show an example of data contents (left side) and display contents (right side) in data transmission between the first device and the second device. The problem that the present invention attempts to resolve is to be found in the second device of an inferior kind.
It is assumed here that data containing lower-case letters are transmitted from the first device to the second device, and then the data received by the second device are reversely transmitted to the first device.
In FIG. 5(A) shows contents of original data DATA1 stored in the first device and display contents based on DATA1 on a display of the first device. The data contents include both upper-case letters and lower-case letters, which are mixed together as follows: EQU DATA1: [A, b, C, d, E, f]
The display contents are identical to the data contents stored: EQU DISP1: {A, b, C, d, E, f}
The data DATA1 are transmitted from the first device to the second device.
In FIG. 5 (B) shows the data contents received by the second device and the display state thereof. As the second device cannot display lower-case letters, lower-case letter codes contained in the data DATA1 are all converted into upper-case letter codes, that is, capitalization is performed when the data DATA1 are received, and the converted data are stored as DATA2 as follows: EQU DATA2: [A, B, C, D, E, F]
Namely, as the above indicates, the lower-case letter codes [b], [d] and [f] are converted into the upper-case letter codes [B], [D] and [F] respectively, and stored.
Accordingly, with the conversion of the lower-case letters into the upper-case letters, the display state of the second device becomes: EQU DISP2: {A, B, C, D, E, F}
Next, capitalized data DATA2 stored in the second device are reversely transmitted to the first device.
In FIG. 5. (C) shows the data contents received by the first device and the display state thereof after reverse transmission from the second device. As data have already been capitalized in the second device as described above, data received by the first device by reverse transmission become: EQU DATA3: [A, B, C, D, E, F]
In accordance with this data, the display state of the first device becomes: EQU DISP3: {A, B, C, D, E, F}
As described above, the second device such as a portable electronic device of an inferior kind, which can only display the alphabet in upper-case letters, converts lower-case letter codes received from the first device of a superior kind such as a portable electronic device or information processing device into upper-case letter codes (i.e., capitalization of the lower-case letters). The resulting problem is that the original lower-case letter codes are changed into upper-case letter codes (letter mutation) when the received data are reversely transmitted to the first device of a superior kind. Namely, in the example above, the original lower-case letter codes [b], [d] and [f] undergo letter mutation, changing into the upper-case letter codes [B], [D] and [F] respectively.
This means that it is not possible to preserve original data, and is a major problem in data transmission. In order to return the data to their original state, it is first necessary to discover which letters have undergone letter mutation. Such an operation is extremely difficult, and considerable time and effort is required to return all subject upper-case letters to lower-case letters.